Grinding wheel crush dressing apparatus



Dec. 10, 1963 D. c. HUGHES 3,113,563

GRINDING WHEEL. CRUSH DRESSING APPARATUS",

Filed April 24, 1961 2 Sheets-Sheet l "IIIHHHHIH""HHIHWWH HIM] ER-RIDE37 ICLUTCH l SPEED REDUCER U 3 45 INVENTOR ANIEL C. UGHES ATTNEY Dec.10, 1963 D. c. HUGHES GRINDING WHEEL CRUSH DRESSING APPARATUS FiledApril 24, 1961 2 Sheets-Sheet 2 INVENTOR DANIEL C. HU G /4 4-1. NEY

United States Patent 3,113,563 GRINDZNG WHEEL CRUSH DRESSENG APPARATUSThe present invention relates to the dressing of grinding wheels, and,more particularly, to crush dressing apparatus for the work wheel of acenterless grinder or the like.

In the past, centerless grinders have been utilized for rapidlyproducing one or more parts which are generally circular incross-section. Such machines generally compn'se a work Wheel or grindingwheel which is con-toured to shape the articles from circular stock, aregulating or feeding wheel for holding the stock against the workwheel, and a work rest for supporting the stock between the Wheel whileit is being ground to the desired shape.

The work whee-l usually is contoured or crush dressed by rotating thesame and forcing against it a freely rotatable wheel of harder materialthan the work wheel which wheel is shaped to produce the desired contouron the work wheel. It has been customary to mount such apparatus at theback of the grinding machine so that the work wheel can be redressedfrom time to time to maintain its contour within close toleranceswithout removing the work wheel from the machine.

In operation of the grinder, the work wheel usually is operated at ahigh speed, for example, at about 2100 r.p.m., and :provision is madefor operating the work wheel at a lower speed, for example at about 50r.p.m. while dressing or redressing the same.

One of the difficulties encountered with such an arrangement is that,when the operator desires to dress or redress the wheel, he may forgetto switch the work wheel drive to the lower operating speed and feedsthe dressing wheel into the work wheel While operating at a high speedwith the result that damage is inflicted to the surface of the workwheel and/ or its bearings.

Accordingly, an object of the present invention is to provide crushdressing apparatus of the foregoing type wherein provision is made forautomatically switching the work wheel drive to its lower speed whenattempt is made to apply the crush dressing wheel to the work wheel andto maintain the drive at that lower speed until the dressing wheel hasbeen retracted.

Another object is to provide such apparatus wherein the dressing wheelcannot be applied to the work Wheel until the work wheel is being drivenat its lower speed.

Another object is to eliminate electrical hazards.

A further object is to accomplish the foregoing in a simple, practical,reliable and economical manner.

Other and further objects of the invention will be obvious upon anunderstanding of the illustrative embodiment about to be described, orwill be indicated in the appended claims, and various advantages notreferred to herein will occur to one skilled in the art upon employmentof the invention in practice.

A preferred embodiment of the invention has been chosen for purposes ofillustration and description, and is shown in the accompanying drawings,forming a part of the specification, wherein:

FIG. 1 is a fragmentary plan View of a grinding machine having crushdressing apparatus attached thereto provided with a drive for operatingthe Work wheel at its higher and lower speeds, and a simplified wiringdiagram for controlling the drive.

:FIG. 2 is an enlarged fragmentary sectional view taken along the line22 on FIG. 1 illustrating a switching arrangement for the drive.

FIG. 3 is a fragmentary perspective View illustrating another switchingarrangement.

FIG. 4 is a sectional view taken horizontally through the switch shownin FIG. 3.

Referring to FIG. 1 of the drawings in detail, there is shown a base 9,a work wheel 10 mounted on the base and drive-n by a motor ll. throughconventional mechanism herein illustrated schematically for simplicityas a chain and sprocket arrangement 12, and work wheel crush dressingapparatus 14 in accordance with the present invention.

The apparatus '14- generally comprises a horizontal bracket 15 which ismounted on the base 9 adjacent an opening =8 in a conventional guard orcasing (partially shown) for the work wheel, a dressing wheel 16,mechanism 117 for moving the dressing wheel into and out of contact withthe work wheel It by way of the opening, and a switching arrangement 11%for the motor.

The dressing wheel do is rotatably supported by bearings 19 on acarriageg 28 which is mounted on a slide 21 supported by the bracket :15between side walls 22 thereof. A threaded spindle 23 is mounted forrotation by a crank or hand wheel 24 at the outer end of the bracket,and the spindle is threaded through the carriage 29 to effect lengthwisemovement thereof along the slide -21.

As shown in FIGS. 1 and 2, the switching arrangement 18 comprises a pinor rod 25 extending transversely through an opening 13 in a side wall 22of the bracket at about the middle thereeof but closer to the inner endof the bracket, a spring 26 for urging the rod 25 inwardly into the pathof the carriage 2d, a switch 27 on the exterior of the side wall of thebracket having an element 28 adapted to be operated by the outer end ofthe rod 25, a spring 33 for maintaining the switch in normally openposition and to cause the element '28 to follow the rod 25, and a cam orwedge 29 at the side of the carriage 24) for operating the rod 25.

The wedge 29 is constructed and arranged so that the rod 25 is operatedby it to close the switch 27 when the carriage approaches a fullyretracted position (FIG. 1) and to allow the switch to open by means ofthe springs 26 and 33 when the dressing wheel '16 approaches the workwheel ll).

Another way of accomplishing this is shown in FIG. 4 which comprisesutilizing the spring 33 in the switch 27 to urge the rod 25 outwardly bythe switch operating element 28, and piviotally mountting a bar or lever30 on the side wall 2% at 31 adapted to be engaged by a pin 32 on thecarriage 20 to close the switch only when the carriage has been fullyretracted.

Preferably, the switching arrangement is so located that the work wheelis operating at its lower speed within the time the dressing wheel canbe moved into engage ment with the work wheel by the relatively slowmovement of the carriage 20 which is effected by the screw threadedspindle 23. it is also within the concept of the present invention thtabraking means under the control of the switching arrangement could beprovided for slowing down the work wheel or its drive to the lower speedat which it is safe to bring the dressing wheel into engagement with thework wheel.

In FIG. 1, a drive for the work wheel It} is shown which includes themain motor 1d having its output connected to the work wheel, anauxiliary motor 34, a speed reducer 3'5, an over-ride clutch 36connected to the out put of the speed reducer, a chain and sprocketdrive 3-7 connecting the output of the motor 34 to the input of thespeed reducer, a chain and sprocket drive 3 8 connecting the over-rideclutch to a counter-shaft 39 of the motor 111, and a control networkabout to be described. With this arrangement, the motor 34 whenenergized while the motor 1 1 is de-energized drives the work wheel atlow speed through the chain and sprocket drive 37, the speed reducer 35,the clutch 36, the chain and sprocket drive 38 and the motor 1 1.However, when the motor 11 is energized and the motor 34 is(lo-energized, the over-ride clutch prevents the motor :11 from drivingthe speed reducer 35.

The control network shown in FIG. 1 includes a relay 40 under thecontrol of the switch 27, a source of power for the motors 1-1 and 34such as lines 41 and 42, a manually operable main switch 44 for turningon and shutting off the source of power, a manually operable switch 45in a branch of the line 41 for starting and stopping the motor 1111, amanually operable switch 46 in another branch of the line 41 forstarting and stopping the motor 34, a double throw switch 47' operatedby the relay 40 for selectively connecting and disconnecting the motors11 and 34 to the line 42 through contacts 48 and 49, respectively, and aswitch arm 56' connected to the line 42, and a transformer 51 connectedacross the lines 41 and 42 for supplying a low voltage for energizingthe relay 40' by means of the switch 27. The low voltage supply andrelay arrangement eliminates the necessity of running the line voltagethrough the switching arrangement 18, whereby electrical hazards in thecrush dressing apparatus is avoided.

In operation, when it is desired to operate the grinding machine, themain switch 44 and the main motor switch 45 are closed. However, if thedressing wheel has not been retracted, the switch 47 will be in aposition whereby the line 42 will not be connected to the motor '11 andthe motor 111 cannot be energized. Upon properly retracting the dressingWheel, the switch 27 will energize the relay 40 to connect the motor 11to the line 42 through the contact 48 and the switch arm 50 as shown inFIG. 1.

When it is desired to dress or redress the Work wheel, the switch 45should be opened, but, if the operator forgets to do so and causes thedressing wheel to move towards the work wheel, the switch 27 opens todeenergize the relay 40* which causes the switch arm '50 to disengagethe contact '48 and to engage the contact 49 whereby the motor 1 1 isautomatically cut out 'md the motor 34 is cut in for low speed operationof the work wheel upon closing of the switch 46.

In the event the operator forgets to open the switch 46 and shut off themotor 34 when it is again desired to operate the grinding machine, thisis efiected automatically by the relay 40 as the dressing wheel isproperly retracted. Consequently, neither the work w eel nor the motor34 and its drive connections to the motor 11 can be dam-aged bycarelessness on the part of the operator.

From the foregoing description, it will be seen that the presentinvention provides improved crush dressing apparatus which does notsubject the operator to a hazardous condition and prevents damage to themachine.

As various changes may be made in the form, construction and arrangementof the parts herein, without departing from the spirit and scope of theinvention and without sacrificing any of its advantages, it is to beunderstood that if, all matter herein is to be interpreted asillustrative and not in any limiting sense.

[I claim:

1. In a centerless grinder, the combination of a work wheel; a supportadjacent said work wheel and extending substantially radially outwardlytherefrom; a horizontally extending slide on said support; a carriageslidably mounted on said slide; crush dressing means mounted on saidcarriage for engaging said work wheel; means for moving said carriagetowards and away from said work wheel; co-operating first and secondmotor means for respectively effecting rotation of said work wheel at aspeed and a much lower speed; and switch means for preventingenergization of said first motor means when said crush dressing meansapproach said work wheel and for selectively energizing andtie-energizing said first and second motor means, said switch meanscomprising at least a control switch, and control switch operating meansincluding a projection on said carriage, movable means having a portionextending into the path of said projection and having a portion foractuating said control switch, spring means for opposing actuation ofsaid control switch and for biasing said movable means to place thefirst mentioned portion thereof into the path of said projection saidprojection and said movable means being arranged to maintain saidcontrol switch in a position to prevent energization of said first motormeans until said carriage has been retracted to move said crushing meansa given distance away from said work wheel, which distance is less thanthe distance said carriage can move on said slide, said first motormeans having a shaft and means on said shaft for effecting rotation ofsaid work wheel, a speed reducer driven by said second motor means, andan over-ride clutch driven by said speed reducer and connection fordriving said shaft at a low speed.

2. A grinder according to claim 1, wherein said first mentioned portionof said movable means is a pivotally mounted lever having a first armengageable by said projection and having a second arm, said secondmentioned portion of said movable means is a slidably mounted rod havinga first end engaging said second arm and having a second end, and saidcontrol switch includes an element engaged by said second end of saidrod.

3. In a centerless grinder according to claim 1, wherein said switchmeans include a low voltage operable relay controlled by said controlswitch, and said control switch is mounted on said support.

References (Zited in the file of this patent UNITED STATES PATENTS2,457,318 Polk Dec. 28, 1948 2,534,941 B aldenhofer Dec. 19, 19502,535,183 Wilson Dec. 26, .1950 2,571,293 Ross Oct. 16, 1951 2,576,201Wilson Nov. 27, 1951 2,586,755 Wilson (Feb. 19, 1952 2,636,321 WilsonApr. 28, 1953 2,652,661 Flanders et al Sept. 22, 1953

1. IN A CENTERLESS GRINDER, THE COMBINATION OF A WORK WHEEL; A SUPPORTADJACENT SAID WORK WHEEL AND EXTENDING SUBSTANTIALLY RADIALLY OUTWARDLYTHEREFROM; A HORIZONTALLY EXTENDING SLIDE ON SAID SUPPORT; A CARRIAGESLIDABLY MOUNTED ON SAID SLIDE; CRUSH DRESSING MEANS MOUNTED ON SAIDCARRIAGE FOR ENGAGING SAID WORK WHEEL; MEANS FOR MOVING SAID CARRIAGETOWARDS AND AWAY FROM SAID WORK WHEEL; CO-OPERATING FIRST AND SECONDMOTOR MEANS FOR RESPECTIVELY EFFECTING ROTATION OF SAID WORK WHEEL AT AHIGH SPEED AND A MUCH LOWER SPEED; AND SWITCH MEANS FOR PREVENTINGENERGIZATION OF SAID FIRST MOTOR MEANS WHEN SAID CRUSH DRESSING MEANSAPPROACH SAID WORK WHEEL AND FOR SELECTIVELY ENERGIZING ANDDE-ENERGIZING SAID FIRST AND SECOND MOTOR MEANS, SAID SWITCH MEANSCOMPRISING AT LEAST A CONTROL SWITCH, AND CONTROL SWITCH OPERATING MEANSINCLUDING A PROJECTION ON SAID CARRIAGE, MOVABLE MEANS HAVING A PORTIONEXTENDING INTO THE PATH OF SAID PROJECTION AND HAVING A PORTION FORACTUATING SAID CONTROL SWITCH, SPRING MEANS FOR OPPOSING ACTUATION OFSAID CONTROL SWITCH AND FOR BIASING SAID MOVABLE MEANS TO PLACE THEFIRST MENTIONED PORTION THEREOF INTO THE PATH OF SAID PROJECTION SAIDPROJECTION AND SAID MOVABLE MEANS BEING ARRANGED TO MAINTAIN SAIDCONTROL SWITCH IN A POSITION TO PREVENT ENERGIZATION OF SAID FIRST MOTORMEANS UNTIL SAID CARRIAGE HAS BEEN RETRACTED TO MOVE SAID CRUSHING MEANSA GIVEN DISTANCE AWAY FROM SAID WORK WHEEL, WHICH DISTANCE IS LESS THANTHE DISTANCE SAID CARRIAGE CAN MOVE ON SAID SLIDE, SAID FIRST MOTORMEANS HAVING A SHAFT AND MEANS ON SAID SHAFT FOR EFFECTING ROTATION OFSAID WORK WHEEL, A SPEED REDUCER DRIVEN BY SAID SECOND MOTOR MEANS, ANDAN OVER-RIDE CLUTCH DRIVEN BY SAID SPEED REDUCER AND CONNECTION FORDRIVING SAID SHAFT AT A LOW SPEED.